Yes it is for real. I have been using #40-4 nylon nuts, bolts, and washers for several years. I buy them at my local hardware store for 11 cents each. Beats the heck out of the old push pins. I learned that trick over at the Asus forums. For my own personal pc I still use an original Thermalright Ultra 120 Extreme tower style cpu heatsink. Works great. I have not experienced any problems.
+1. I do this as well (tanks to you,btw), esp, when there aren't any bolt in kits available for that model.